window.onload = function () {
			alertarusuario("1");
		}
		
		function alertarusuario(valor){
		    if(valor == 1){
		    	document.getElementById('1').style.display="block";
				document.getElementById('2').style.display="none";
				document.getElementById('3').style.display="none";
				document.getElementById("1").disabled = false; //Habilitando
				document.getElementById("2").disabled = true; //Desabilitando 
				document.getElementById("3").disabled = true; //Desabilitando 
		    }else if(valor == 2){
		    	document.getElementById('1').style.display="none";
				document.getElementById('2').style.display="block";
				document.getElementById('3').style.display="none";
				document.getElementById("2").disabled = false; //Habilitando
				document.getElementById("1").disabled = true; //Desabilitando 
				document.getElementById("3").disabled = true; //Desabilitando 
		    }else if(valor == 3){
		    	document.getElementById('1').style.display="none";
				document.getElementById('2').style.display="none";
				document.getElementById('3').style.display="block";
				document.getElementById("3").disabled = false; //Habilitando
				document.getElementById("2").disabled = true; //Desabilitando 
				document.getElementById("1").disabled = true; //Desabilitando 
		    }
		}